Telephone system



Feb. 10, 1931. I BELLAMY 1,791,702

TELEPHONE SYSI'EII Original Filed July 2. 1928 70 510W ALARM Patented Feb. '10, 1931 u ren srrs JOHN I.

IBELLAMY, or BROOKFIELD, ILLINOIS, 'ASSIGNOR To RESERVE HOLDING COMPANY, or KANSAS CITY, MIssOUnI, A CORPORATION OF DELAWARE TELEPHONE SYSTEM I Application filed July 2, 1928, Serial No. 289,766. Renewed. May 17,.1930.

The present invention relates to new and improved selector switches for use in telephone systems, but is concerned more particularly with selector switches of the so- 5 called two-wire type in which one of the slow acting control relays is shunted to secure its deenergization and in which both of. the slow acting control relays depend upon selfinduced circulating currents for their slow action during the directed operation of the switch.

The broad general object of the invention is the production of a new and improved selector circuit of the above type which incorporates all the features required in a standard selector.

More in particular, one object of the invention is the provision of a suitable arrangement for a selector wherein the change-over relay draws currentin parallel with the operating magnet for utilizing a single winding for Operating the relay during the setting of the selector and for reoperating the relay during the release of the selector so as to guard the selector against seizure during release.

Another object is the provision of circuit arrangements excluding the release. magnet and effective only during the releasing operation of the switch for giving a signal in case the selector fails to release properly.

Referring now to the accompanying drawings comprising a single sheet, the selector shown therein in accordance with the usual circuit diagrams incorporates the features of the invention. In this selector, relay A is the usual line relay; relay B is the usual release relay; relay C is the usual changeover relay; relay D is the usual stepping relay; relay E is the usual switching relay; magnet V is the vertical magnet; magnet RO is the usual rotary magnet; and the magnet BL is the usual release magnet.

Detailed description For, this purpose it will be assumed that the selectoris seized in the usual manner over conductors 13., 23, and 33.

Seizure of selector When the selector is seized, line relay A operates over conductors 13 and 33 in series and closes a circuit for relay B which includes magnet V. Relay B energizes, but the magnet V does not operatively energize due to the relatively high resistance of relay B." It will be noted that a momentary"circuit is closed for magnet V while all .three' contacts of relay A are together while the relay is pull.- ing up, but this conditionexists. for so short a time that magnet B does not operate. :Re- I lay C, in serieswith magnet BL, is in parallel with-magnet V but does notoperate because it is in series with relay B and is shunted by magnet V.-

At its upper armature, relay B places a ground potential on the release trunk. conductor 23 for guarding and-holdingpurposes,

while at its lower armature it opens 1-point in the circuit of release magnet RL and closes a locking circuit foritself, thereby preparing an; operating circuit for the magnet B and relay C as will hereinafter appear.

Setting operation 7 When the selector is to be Operated, a series of interruptionsis produced in the circuit of the line relay (usually by the calling device on the calling line), whereupon relay A falls back each time its circuit is interrupted. Each-time it falls backrelay A opens the initial circuitof relay B, but relay B is locked, at its lower armature, to ground through the inner lower contacts of relay E. ,As a further result of each deenergizatio-n of relay A, it short circuits relay B, extending the ground potential applied through the inner lower contacts of relay E and the lower armature, Operated, of relay B to the vertical magnet V and relay OJ Relay C and the vertical magnet both operate when relay B is short circuited. The proportion of the windings concerned is such that the vertical magnet V restores immediately upon each reoperation of relay A when the shunt is removed from around relay B, but relay C (even though it is adjusted so that it will not hold up indefinitely through relayBin parallel with magnet V) holds up throughout the train of impulses supplied to it and to the vertical magnet, due to the fact that the current flow through the relay attenuates slowly. Relay B holds up during the deenerg'izations of relay A. even. though short circuited. due to the circulating current through its winding. Magnet BL is not operated at this time due to the relatively hi h resistance of relav C.

By the operation of the vertical magnet V the wipers shown to the right of the circuit are raised step by step in the usual manner until they come to restopposite the desired level of bank contacts. Upon the oft-normal movement of the switch. a circuit is completed at the oil-normal contacts associated with relay D through the interrupter contacts and contacts of relay C for relay D. whereupon relay D operates and locks itself through its interrupter contacts and the associated offnormal contacts to the grounded release trunk conductor23.

. Trunk hunting Shortly after the line relay comes to rest in an energized condition at the end of the impulse series. relay C falls back and connects up the test wipers at the junction of relays D and E. at the same time opening the initial circuit of the locked-up relay D and closing a circuit through the contacts of relay D for the rotary magnet R0. The rotary magnet operates and advances the wipers into engagement with the first set of bank contacts in the level opposite which they were raised. Near the end of its stroke, ma 5:- net ROopens the circuit of relay D. whereupon relay D falls back. In case the first trunk line is idle, the rotary operation does not proceed further and relay E operates in a manner to be hereinafter pointed out.

Assuming that the first trunk line isbusy, a ground potential is encountered bvthe test wiper. the middle wiper. closing a circuit through contacts of relays E andC forrelav D through the interrupter and oitnormal contacts, whereupon relay D again operates and locks itself. at the same time closing a circuit for the rotary magnet. The rotary magnet operates and advances its wipers another step.

Trunk seizure rupter and off-normal contacts in series with stepping relay D. Relay D does not operate at this time owing to the relatively high re-' sistance of relay E. At its inner lower armature, relay E removes ground potential from test wiper to grounded release-trunk conductor 23, while at its upper and lower armatures it disconnects the incoming conductors 13 and 33 from the windings of line relay A and extends them through the upper and lower wipers to the corresponding conductors of the seized trunk line.

Line relay A now falls back and opens circuits and short circuits relay B, with the result that relay B shortly falls back and prepares the release magnet circuit at its lower armature, at the same time'removing ground potential from release-trunk conductor 23 at its inner upper armature. It will be understood of course that, before relay B can fall back ground potential has been applied to the extended release-trunk conductor by the apparatus connected to the seized trunk line.

Releasing operation When the selector is to be released, the potential is removed from the release-trunk conductor of the established connection, whereupon relay E falls back and completes the release magnet circuit at its inner lower armature. 'Relay C is operated in parallel with the release magnet and in series with the vertical magnet at this time, but the vertical magnet V is not operated due to the relatively high resistance of relay C. Upon reopei'ating relay C closes a circuit for relay D through the interrupter contacts of themagnet R0 and the off-normal contacts associated with relay D, whereupon relay D reoperates and applies the ground potential applied to its windings to the release-trunk conductor 23, thereby, guarding the selector from seizure from the releasing operation.

lVhen the normal position of the selector is reached, the oil-normal contacts 7 open whereupon the release magnet RL deenergizes and relays C and D fallback. The selector is now in readiness to be used again.

Supervisory signals Regarding the signals by means of which an attendant supervises the operation of switching apparatus, the supervisory lamp L1 is common to a plurality of selectors and is lighted whenever the release relay of any one of them is energized. This is the usual arrangement for selectors of this type. The supervisory lamp L2 connected in the associated conductor leading to the slow alarm is provided for indicating the particular til) Hit)

of selectorsin which a trouble condi-' tion enists' when, due perhaps to a bad adustment of the wipers causing them to stick on the bank, a selector fails' to release when tion of the selector because, even though relay C] is operated at this time, the circuit is not closed through the lamp L2 owing to the fact that relay B is operated. What is claimed is: w V

' 1 In an automaticswitch, a vertical magnet, a release magnet, a relay having a single winding permanentlyconnected to each magnet, and circuit connections for operating the relay through, said winding in parallel with the vertical magnet and in series with the release magnet during the setting operation of the switch and for operating the relayinparallel with the release magnet and in series with the vertical magnet during the releasing operation of the switch.

2. In an automatic switch having an operating magnet and a release magnet both connected to a common source of potential, a control relay connected between the free terminals of the magnets, and circuit connections for applying the other pole of said potential source to the free terminal of either of said magnets, the said relay being of such a resistance value that neither of said magnets will operate in series with it while it operates in series with either magnet.

3. In a selector switch for use in a telephone system, an operating magnet, a release magnet, a control relay, and circuit connections for operating said control relay in a circuit parallel to the circuit of the oper-. ating magnet during the setting operation of the switch and for operating the control relay in a circuit parallel to the circuit of' the release magnet during the releasing operation of the switch.

4. In an automatic switch arranged to be set in accordance With a desired telephone number to extend a telephone connection and to be released when the connection is no longer desired, a release relay and circuit connections for maintaining it operated while the switch is being operated to set up so that it is rendered effective only during the releasing operation of the switch. 5. In an automatic switch arranged to be set in accordance with a desired telephone number to efitend a'telephone connection and to be released when the connection is no longer des1red,a release relay and circuit connections for maintaimng it operated while the switch is being operate-d to set up the connection, a control relay and circuit connections for reoperating it during the reieasmg'operation of the switch, and a signal circuit passing through front contacts of said I control relay and back contacts of said 'release relay; I V

6. In an automatic switch arrangedto be set in accordance witha de'sired telephone number to extend a telephone connection and to be released when the connection is no longer desired, a release relay and circuit connections formamtammg it operated while the switch is being operated to set up 7 the connection, a control'relay and circuit connectionsfor reoperating it during the releasing operation of the switch, a signal circuit passing through front contacts of said" release" relay, andanother signal circuit passing through the back contacts of said release relay "and through the front contacts of said control relay.

*7. an automatic switch arranged. to be set "ina desired position andto be subsequently released to normal, :airelease' magnet and a circuit including oii-normal contacts of thefswitch for energiZingJit to release the switch, a relay. arranged to beoperated in paralletwith saidirelease magnetf-a signal, andmeans'including circuit connections controlled by said re'l'ay for operating said'signal'in case said release-magnet "circuit re- 8. In an automatic 'switcln'a fel ay,'m e ans for operating said relay during the setting operationof saidswitch and for reoperating it duringlthe releasing f operation of ,said

switch, a signal circuit closed through contacts of said relay when itis reoperatedduring the releasing operationof the switch, and means for preventing a closure of said circuit when 'saidsrelay is operated. during the setting operation ofthe switch. .I 9..In' an automatic switch, an operating magnet'and a control relay connected in parallel circuits, means for closing acircuit to operate"- the relay as a changeover relay in parallel with the magnet, and means "for 'sub 'sequentlyoperating the-relay in series with the magnet. I

' 10. In an automatic switch, an operating magnet and a'control relay connected in parallel circuits, means for closing a circuit to operate the relay as a changeover relayin parallel with themagn'et, and means for sub mains closed for longer a predetermined sequently operating the relay in series with the magnet Without ope-rating the magnet.

11. In a selector switch for use in a switching system, means fortaking said selector for use and for marking it busy while it is in use, means for operating said selector, a release magnet and means for operating the release magnet to release the selector after it has been used, a relay connected in a circuit in parallel with the release magnet, and means including contacts on said relay for marking the selector busy while it is being released.

12. In a selector, an incoming trunk line including a test conductor, a release magnet and means for operating it to release the selector, acontrol relay and means for operating it in a circuit parallel to the circuit of the release magnet, a second relay arranged to apply a guarding potential to the incoming test conductor, and means for operating the second relay responsive to the operation of said control relay.

13. In a selector, primary and secondary operating magnets, a control relay, circuit connections for operating said relay in parallel with the primary operating magnet to control the changeover from primary-magnet operation to secondary-magnet operation, means for releasing the selector, and means for reo-perating said relay in series with the primary magnet to guard theselector from seizure while it is being released.

' 14. In a selector, a release relay and'a re lease magnet, means for operating saidrelease relay, and contacts" on the release relay for closing a locking circuit for itself in series with said release magnet.

15. In a selector, a release relay, a control relay, and a release magnet; means for operating said release relay, and contacts on said release-relay for locking itself in series with said control relay and said release magnet.

16. In a selector, a release relay, a control relay, and a release magnet; and means for operating said release relay in circuit with said control relay and release'magnet.

17. In a selector, a release relay and an operating magnet, means for operating said re lease relay in series with said operating magnet, a release magnet, a circuit parallel to the circuit of the operating magnet including said release magnet, means for shunting said release relay to operate said operating mags net, and a resistance element included in circuit in series with. said release magnet for preventing the operation of the release magnet.

18. In an automatic switch, two magnets, a relay, means for operating said relay in parallel with the first magnet and in series with the second magnet and for subsequently operating said relay in parallel with the second magnet and in series with the first magnet, and contacts on said relay arranged to perform one function the first time the relay is operated and to perform another function the second time the relay is operated.

19. In a selector, two magnets and a relay, means for operating said relay in parallel with the first magnet and in series with the second magnet, means for operating said relay in parallel with the second magnet and in series with the first magnet, and contacts on said relay arranged to control a function of the selector each time the relay is operated.

20. In a selector, a, release relay and a changeover relay, a signal circuit controlled by the release relay independent of the changeover relay, and another signal circuit controlled by the two relays jointly.

21. In a selector, an operating magnet, a relay arranged to be operated in series with said magnet and another relay arranged to be operated in parallel with said magnet, and a signal circuit controlled by said relays jointly.

22. In a selector a release relay and a control relay, an alarm device, and a circuit for said alarm device controlled by said relays jointly.

In witness whereof, I hereunto subscribe my name this 28th day of June, A. D. 1928.

' JOHN I. BELLAMY. 

